| [assume Great Britain unless specifed] | |
| Principal Triangulation (published in 1858) | |
| First primary levelling (+) | |
| original levelling - Ireland | |  |
| subsequent levelling - Ireland | | |
| Second geodetic levelling - England & Wales (+) | |  |  |
| (World War One) | |
| Measurement of the Ordnance Datum Newlyn | |
| Relevelling of Greater London | |
| Retriangulation of Great Britain (published 1967) (+) | |
| Second geodetic levelling - Scotland | |  |
| (2nd World War) | |
| Second geodetic levelling - East Anglia and Kent | |
| Third geodetic levelling - England & Wales | | | |
| Third geodetic levelling - Scotland | | |
| Cyclic relevelling - England & Wales | | | |
| Cyclic relevelling - Scotland | | |
| Retriangulation - Ireland | | |
| Readjustment of the Triangulation | |
| Further Triangulation | |
| GPS era | |
| GPS era | |
| [assume Great Britain unless specifed] | |
